fs/hfsplus/btree.c

   1 /*
   2  *  linux/fs/hfsplus/btree.c
   3  *
   4  * Copyright (C) 2001
   5  * Brad Boyer (flar@allandria.com)
   6  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   7  *
   8  * Handle opening/closing btree
   9  */
  10
  11 #include <linux/slab.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/log2.h>
  14
  15 #include "hfsplus_fs.h"
  16 #include "hfsplus_raw.h"
  17
  18
  19 /* Get a reference to a B*Tree and do some initial checks */
  20 struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id)
  21 {
  22         struct hfs_btree *tree;
  23         struct hfs_btree_header_rec *head;
  24         struct address_space *mapping;
  25         struct page *page;
  26         unsigned int size;
  27
  28         tree = kzalloc(sizeof(*tree), GFP_KERNEL);
  29         if (!tree)
  30                 return NULL;
  31
  32         init_MUTEX(&tree->tree_lock);
  33         spin_lock_init(&tree->hash_lock);
  34         tree->sb = sb;
  35         tree->cnid = id;
  36         tree->inode = iget(sb, id);
  37         if (!tree->inode)
  38                 goto free_tree;
  39
  40         mapping = tree->inode->i_mapping;
  41         page = read_mapping_page(mapping, 0, NULL);
  42         if (IS_ERR(page))
  43                 goto free_tree;
  44
  45         /* Load the header */
  46         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
  47         tree->root = be32_to_cpu(head->root);
  48         tree->leaf_count = be32_to_cpu(head->leaf_count);
  49         tree->leaf_head = be32_to_cpu(head->leaf_head);
  50         tree->leaf_tail = be32_to_cpu(head->leaf_tail);
  51         tree->node_count = be32_to_cpu(head->node_count);
  52         tree->free_nodes = be32_to_cpu(head->free_nodes);
  53         tree->attributes = be32_to_cpu(head->attributes);
  54         tree->node_size = be16_to_cpu(head->node_size);
  55         tree->max_key_len = be16_to_cpu(head->max_key_len);
  56         tree->depth = be16_to_cpu(head->depth);
  57
  58         /* Set the correct compare function */
  59         if (id == HFSPLUS_EXT_CNID) {
  60                 tree->keycmp = hfsplus_ext_cmp_key;
  61         } else if (id == HFSPLUS_CAT_CNID) {
  62                 if ((HFSPLUS_SB(sb).flags & HFSPLUS_SB_HFSX) &&
  63                     (head->key_type == HFSPLUS_KEY_BINARY))
  64                         tree->keycmp = hfsplus_cat_bin_cmp_key;
  65                 else {
  66                         tree->keycmp = hfsplus_cat_case_cmp_key;
  67                         HFSPLUS_SB(sb).flags |= HFSPLUS_SB_CASEFOLD;
  68                 }
  69         } else {
  70                 printk(KERN_ERR "hfs: unknown B*Tree requested\n");
  71                 goto fail_page;
  72         }
  73
  74         size = tree->node_size;
  75         if (!is_power_of_2(size))
  76                 goto fail_page;
  77         if (!tree->node_count)
  78                 goto fail_page;
  79         tree->node_size_shift = ffs(size) - 1;
  80
  81         tree->pages_per_bnode = (tree->node_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
  82
  83         kunmap(page);
  84         page_cache_release(page);
  85         return tree;
  86
  87  fail_page:
  88         tree->inode->i_mapping->a_ops = &hfsplus_aops;
  89         page_cache_release(page);
  90  free_tree:
  91         iput(tree->inode);
  92         kfree(tree);
  93         return NULL;
  94 }
  95
  96 /* Release resources used by a btree */
  97 void hfs_btree_close(struct hfs_btree *tree)
  98 {
  99         struct hfs_bnode *node;
 100         int i;
 101
 102         if (!tree)
 103                 return;
 104
 105         for (i = 0; i < NODE_HASH_SIZE; i++) {
 106                 while ((node = tree->node_hash[i])) {
 107                         tree->node_hash[i] = node->next_hash;
 108                         if (atomic_read(&node->refcnt))
 109                                 printk(KERN_CRIT "hfs: node %d:%d still has %d user(s)!\n",
 110                                         node->tree->cnid, node->this, atomic_read(&node->refcnt));
 111                         hfs_bnode_free(node);
 112                         tree->node_hash_cnt--;
 113                 }
 114         }
 115         iput(tree->inode);
 116         kfree(tree);
 117 }
 118
 119 void hfs_btree_write(struct hfs_btree *tree)
 120 {
 121         struct hfs_btree_header_rec *head;
 122         struct hfs_bnode *node;
 123         struct page *page;
 124
 125         node = hfs_bnode_find(tree, 0);
 126         if (IS_ERR(node))
 127                 /* panic? */
 128                 return;
 129         /* Load the header */
 130         page = node->page[0];
 131         head = (struct hfs_btree_header_rec *)(kmap(page) + sizeof(struct hfs_bnode_desc));
 132
 133         head->root = cpu_to_be32(tree->root);
 134         head->leaf_count = cpu_to_be32(tree->leaf_count);
 135         head->leaf_head = cpu_to_be32(tree->leaf_head);
 136         head->leaf_tail = cpu_to_be32(tree->leaf_tail);
 137         head->node_count = cpu_to_be32(tree->node_count);
 138         head->free_nodes = cpu_to_be32(tree->free_nodes);
 139         head->attributes = cpu_to_be32(tree->attributes);
 140         head->depth = cpu_to_be16(tree->depth);
 141
 142         kunmap(page);
 143         set_page_dirty(page);
 144         hfs_bnode_put(node);
 145 }
 146
 147 static struct hfs_bnode *hfs_bmap_new_bmap(struct hfs_bnode *prev, u32 idx)
 148 {
 149         struct hfs_btree *tree = prev->tree;
 150         struct hfs_bnode *node;
 151         struct hfs_bnode_desc desc;
 152         __be32 cnid;
 153
 154         node = hfs_bnode_create(tree, idx);
 155         if (IS_ERR(node))
 156                 return node;
 157
 158         tree->free_nodes--;
 159         prev->next = idx;
 160         cnid = cpu_to_be32(idx);
 161         hfs_bnode_write(prev, &cnid, offsetof(struct hfs_bnode_desc, next), 4);
 162
 163         node->type = HFS_NODE_MAP;
 164         node->num_recs = 1;
 165         hfs_bnode_clear(node, 0, tree->node_size);
 166         desc.next = 0;
 167         desc.prev = 0;
 168         desc.type = HFS_NODE_MAP;
 169         desc.height = 0;
 170         desc.num_recs = cpu_to_be16(1);
 171         desc.reserved = 0;
 172         hfs_bnode_write(node, &desc, 0, sizeof(desc));
 173         hfs_bnode_write_u16(node, 14, 0x8000);
 174         hfs_bnode_write_u16(node, tree->node_size - 2, 14);
 175         hfs_bnode_write_u16(node, tree->node_size - 4, tree->node_size - 6);
 176
 177         return node;
 178 }
 179
 180 struct hfs_bnode *hfs_bmap_alloc(struct hfs_btree *tree)
 181 {
 182         struct hfs_bnode *node, *next_node;
 183         struct page **pagep;
 184         u32 nidx, idx;
 185         u16 off, len;
 186         u8 *data, byte, m;
 187         int i;
 188
 189         while (!tree->free_nodes) {
 190                 struct inode *inode = tree->inode;
 191                 u32 count;
 192                 int res;
 193
 194                 res = hfsplus_file_extend(inode);
 195                 if (res)
 196                         return ERR_PTR(res);
 197                 HFSPLUS_I(inode).phys_size = inode->i_size =
 198                                 (loff_t)HFSPLUS_I(inode).alloc_blocks <<
 199                                 HFSPLUS_SB(tree->sb).alloc_blksz_shift;
 200                 HFSPLUS_I(inode).fs_blocks = HFSPLUS_I(inode).alloc_blocks <<
 201                                              HFSPLUS_SB(tree->sb).fs_shift;
 202                 inode_set_bytes(inode, inode->i_size);
 203                 count = inode->i_size >> tree->node_size_shift;
 204                 tree->free_nodes = count - tree->node_count;
 205                 tree->node_count = count;
 206         }
 207
 208         nidx = 0;
 209         node = hfs_bnode_find(tree, nidx);
 210         if (IS_ERR(node))
 211                 return node;
 212         len = hfs_brec_lenoff(node, 2, &off);
 213
 214         off += node->page_offset;
 215         pagep = node->page + (off >> PAGE_CACHE_SHIFT);
 216         data = kmap(*pagep);
 217         off &= ~PAGE_CACHE_MASK;
 218         idx = 0;
 219
 220         for (;;) {
 221                 while (len) {
 222                         byte = data[off];
 223                         if (byte != 0xff) {
 224                                 for (m = 0x80, i = 0; i < 8; m >>= 1, i++) {
 225                                         if (!(byte & m)) {
 226                                                 idx += i;
 227                                                 data[off] |= m;
 228                                                 set_page_dirty(*pagep);
 229                                                 kunmap(*pagep);
 230                                                 tree->free_nodes--;
 231                                                 mark_inode_dirty(tree->inode);
 232                                                 hfs_bnode_put(node);
 233                                                 return hfs_bnode_create(tree, idx);
 234                                         }
 235                                 }
 236                         }
 237                         if (++off >= PAGE_CACHE_SIZE) {
 238                                 kunmap(*pagep);
 239                                 data = kmap(*++pagep);
 240                                 off = 0;
 241                         }
 242                         idx += 8;
 243                         len--;
 244                 }
 245                 kunmap(*pagep);
 246                 nidx = node->next;
 247                 if (!nidx) {
 248                         printk(KERN_DEBUG "hfs: create new bmap node...\n");
 249                         next_node = hfs_bmap_new_bmap(node, idx);
 250                 } else
 251                         next_node = hfs_bnode_find(tree, nidx);
 252                 hfs_bnode_put(node);
 253                 if (IS_ERR(next_node))
 254                         return next_node;
 255                 node = next_node;
 256
 257                 len = hfs_brec_lenoff(node, 0, &off);
 258                 off += node->page_offset;
 259                 pagep = node->page + (off >> PAGE_CACHE_SHIFT);
 260                 data = kmap(*pagep);
 261                 off &= ~PAGE_CACHE_MASK;
 262         }
 263 }
 264
 265 void hfs_bmap_free(struct hfs_bnode *node)
 266 {
 267         struct hfs_btree *tree;
 268         struct page *page;
 269         u16 off, len;
 270         u32 nidx;
 271         u8 *data, byte, m;
 272
 273         dprint(DBG_BNODE_MOD, "btree_free_node: %u\n", node->this);
 274         BUG_ON(!node->this);
 275         tree = node->tree;
 276         nidx = node->this;
 277         node = hfs_bnode_find(tree, 0);
 278         if (IS_ERR(node))
 279                 return;
 280         len = hfs_brec_lenoff(node, 2, &off);
 281         while (nidx >= len * 8) {
 282                 u32 i;
 283
 284                 nidx -= len * 8;
 285                 i = node->next;
 286                 hfs_bnode_put(node);
 287                 if (!i) {
 288                         /* panic */;
 289                         printk(KERN_CRIT "hfs: unable to free bnode %u. bmap not found!\n", node->this);
 290                         return;
 291                 }
 292                 node = hfs_bnode_find(tree, i);
 293                 if (IS_ERR(node))
 294                         return;
 295                 if (node->type != HFS_NODE_MAP) {
 296                         /* panic */;
 297                         printk(KERN_CRIT "hfs: invalid bmap found! (%u,%d)\n", node->this, node->type);
 298                         hfs_bnode_put(node);
 299                         return;
 300                 }
 301                 len = hfs_brec_lenoff(node, 0, &off);
 302         }
 303         off += node->page_offset + nidx / 8;
 304         page = node->page[off >> PAGE_CACHE_SHIFT];
 305         data = kmap(page);
 306         off &= ~PAGE_CACHE_MASK;
 307         m = 1 << (~nidx & 7);
 308         byte = data[off];
 309         if (!(byte & m)) {
 310                 printk(KERN_CRIT "hfs: trying to free free bnode %u(%d)\n", node->this, node->type);
 311                 kunmap(page);
 312                 hfs_bnode_put(node);
 313                 return;
 314         }
 315         data[off] = byte & ~m;
 316         set_page_dirty(page);
 317         kunmap(page);
 318         hfs_bnode_put(node);
 319         tree->free_nodes++;
 320         mark_inode_dirty(tree->inode);
 321 }